才能是来自独创性。独创性是思维、观察、理解和判断的一种独特的方式。
ile Uploading is a very common task in any web application. We have earlier seen how to upload files in Servlet and Struts2 File Uploading. Today we will learn how to upload single and multiple files in Spring framework.
Spring MVC framework provide support for uploading files by integrating Apache Commons FileUpload API. The process to upload files is very easy and requires simple configurations. We will create a simple Spring MVC project in STS that will look like below image.
Most of the part is the boiler-plate code generated by STS tool, we will focus into the changes that are required to utilize Spring file upload integration.
First of all we need to add Apache Commons FileUpload dependencies in our pom.xml file, so that required jar files are part of the web application.
<!-- Apache Commons FileUpload --> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3.1</version> </dependency> <!-- Apache Commons IO --> <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>2.4</version> </dependency>
We will create two JSP pages to allow single and multiple file uploads.
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <%@ page session="false" %> <html> <head> <title>Upload File Request Page</title> </head> <body> <form method="POST" action="uploadFile" enctype="multipart/form-data"> File to upload: <input type="file" name="file"><br /> Name: <input type="text" name="name"><br /> <br /> <input type="submit" value="Upload"> Press here to upload the file! </form> </body> </html>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <%@ page session="false" %> <html> <head> <title>Upload Multiple File Request Page</title> </head> <body> <form method="POST" action="uploadMultipleFile" enctype="multipart/form-data"> File1 to upload: <input type="file" name="file"><br /> Name1: <input type="text" name="name"><br /> <br /> File2 to upload: <input type="file" name="file"><br /> Name2: <input type="text" name="name"><br /> <br /> <input type="submit" value="Upload"> Press here to upload the file! </form> </body> </html>
Notice that these files are simple HTML files, I am not using any JSP or Spring tags to avoid complexity. The important point to note is that form enctype should be multipart/form-data, so that Spring web application knows that the request contains file data that needs to be processed.
Also note that for multiple files, the form field “file” and “name” are same in the input fields, so that the data will be sent in the form of array. We will take the input array and parse the file data and store it in the given file name.
To utilize Apache Commons FileUpload for handling multipart requests, all we need to do is configuremultipartResolver bean with class as org.springframework.web.multipart.commons.CommonsMultipartResolver.
Our final Spring configuration file looks like below.
<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!-- DispatcherServlet Context: defines this servlet's request-processing
infrastructure -->
<!-- Enables the Spring MVC @Controller programming model -->
<annotation-driven />
<!-- Handles HTTP GET requests for /resources/** by efficiently serving
up static resources in the ${webappRoot}/resources directory -->
<resources mapping="/**" location="/" />
<!-- Resolves views selected for rendering by @Controllers to .jsp resources
in the /WEB-INF/views directory -->
<beans:bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<beans:property name="prefix" value="/WEB-INF/views/" />
<beans:property name="suffix" value=".jsp" />
</beans:bean>
<beans:bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- setting maximum upload size -->
<beans:property name="maxUploadSize" value="100000" />
</beans:bean>
<context:component-scan base-package="com.journaldev.spring.controller" />
</beans:beans>
Notice that I am setting maximum upload size limit by providing the maxUploadSize property value formultipartResolver bean. If you will look into the source code of DispatcherServlet class, you will see that a MultipartResolver variable with name multipartResolver is defined and initialized in below method.
private void initMultipartResolver(ApplicationContext context)
{
try
{
this.multipartResolver = ((MultipartResolver)context.getBean("multipartResolver", MultipartResolver.class));
if (this.logger.isDebugEnabled()) {
this.logger.debug("Using MultipartResolver [" + this.multipartResolver + "]");
}
}
catch (NoSuchBeanDefinitionException ex)
{
this.multipartResolver = null;
if (this.logger.isDebugEnabled())
this.logger.debug("Unable to locate MultipartResolver with name 'multipartResolver': no multipart request handling provided");
}
}
With this configuration, any request with enctype as multipart/form-data will be handled by multipartResolver before passing on to the Controller class.
Controller class code is very simple, we need to define handler methods for the uploadFile anduploadMultipleFile URIs.
package com.journaldev.spring.controller;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
/**
* Handles requests for the application file upload requests
*/
@Controller
public class FileUploadController {
private static final Logger logger = LoggerFactory
.getLogger(FileUploadController.class);
/**
* Upload single file using Spring Controller
*/
@RequestMapping(value = "/uploadFile", method = RequestMethod.POST)
public @ResponseBody
String uploadFileHandler(@RequestParam("name") String name,
@RequestParam("file") MultipartFile file) {
if (!file.isEmpty()) {
try {
byte[] bytes = file.getBytes();
// Creating the directory to store file
String rootPath = System.getProperty("catalina.home");
File dir = new File(rootPath + File.separator + "tmpFiles");
if (!dir.exists())
dir.mkdirs();
// Create the file on server
File serverFile = new File(dir.getAbsolutePath()
+ File.separator + name);
BufferedOutputStream stream = new BufferedOutputStream(
new FileOutputStream(serverFile));
stream.write(bytes);
stream.close();
logger.info("Server File Location="
+ serverFile.getAbsolutePath());
return "You successfully uploaded file=" + name;
} catch (Exception e) {
return "You failed to upload " + name + " => " + e.getMessage();
}
} else {
return "You failed to upload " + name
+ " because the file was empty.";
}
}
/**
* Upload multiple file using Spring Controller
*/
@RequestMapping(value = "/uploadMultipleFile", method = RequestMethod.POST)
public @ResponseBody
String uploadMultipleFileHandler(@RequestParam("name") String[] names,
@RequestParam("file") MultipartFile[] files) {
if (files.length != names.length)
return "Mandatory information missing";
String message = "";
for (int i = 0; i < files.length; i++) {
MultipartFile file = files[i];
String name = names[i];
try {
byte[] bytes = file.getBytes();
// Creating the directory to store file
String rootPath = System.getProperty("catalina.home");
File dir = new File(rootPath + File.separator + "tmpFiles");
if (!dir.exists())
dir.mkdirs();
// Create the file on server
File serverFile = new File(dir.getAbsolutePath()
+ File.separator + name);
BufferedOutputStream stream = new BufferedOutputStream(
new FileOutputStream(serverFile));
stream.write(bytes);
stream.close();
logger.info("Server File Location="
+ serverFile.getAbsolutePath());
message = message + "You successfully uploaded file=" + name
+ "<br />";
} catch (Exception e) {
return "You failed to upload " + name + " => " + e.getMessage();
}
}
return message;
}
}
Notice the use of Spring annotations that make our life easier and code looks more readable.
uploadFileHandler method is used to handle single file upload scenario whereas uploadMultipleFileHandler method is used to handle multiple files upload scenario. Actually we could have a single method to handle both the scenarios.
Now export the application as WAR file and deploy it into Tomcat servlet container.
When we run our application, below images shows us the request and responses.
You can check the server logs to know the location where the files have been stored.
Download the project from above link and play around with it to learn more.
